Unable to retrieve workflow instance

I'm having the exact same issue described in this ticket, which for some reason is ready only now: http://forums.adobe.com/message/5494990

In summary, I have a workflow that recently started throwing exception whenever I try to run it:

20.02.2014 10:34:01.901 *ERROR* [ObservationManager] com.adobe.granite.workflow.core.model.WorkflowModelCacheImpl cannot load model. id: [workflow-path]/jcr:content/model vid: 1.11 20.02.2014 10:34:01.901 *WARN* [ObservationManager] com.adobe.granite.workflow.core.eventsupport.JcrToWorkflowEventService Unable to retrieve workflow instance: /etc/workflow/instances/2014-02-20/model_2924610957186695 com.adobe.granite.workflow.WorkflowException: Unable to retrieve workflow instance: /etc/workflow/instances/2014-02-20/model_2924610957186695 at com.adobe.granite.workflow.core.jcr.WorkflowManager.getWorkflowInstance(WorkflowManager.java:112) at com.adobe.granite.workflow.core.WorkflowSessionImpl.getWorkflow(WorkflowSessionImpl.java:578) at com.adobe.granite.workflow.core.eventsupport.JcrToWorkflowEventService.onEvent(JcrToWorkflowEventService.java:175) at org.apache.jackrabbit.core.observation.EventConsumer.consumeEvents(EventConsumer.java:249) at org.apache.jackrabbit.core.observation.ObservationDispatcher.run(ObservationDispatcher.java:161) at java.lang.Thread.run(Thread.java:722) Caused by: com.adobe.granite.workflow.model.VersionException: Version 1.11 does not exist for [workflow-path]/jcr:content/model at com.adobe.granite.workflow.core.jcr.WorkflowModelManager.getWorkflowModel(WorkflowModelManager.java:96) at com.adobe.granite.workflow.core.WorkflowSessionImpl.getModel(WorkflowSessionImpl.java:279) at com.adobe.granite.workflow.core.util.NodeReader.createWorkflow(NodeReader.java:211) at com.adobe.granite.workflow.core.jcr.WorkflowManager.getWorkflowInstance(WorkflowManager.java:110) ... 5 more 20.02.2014 10:34:01.902 *ERROR* [ObservationManager] com.adobe.granite.workflow.core.model.WorkflowModelCacheImpl cannot load model. id: [workflow-path]/jcr:content/model vid: 1.11 20.02.2014 10:34:01.902 *WARN* [ObservationManager] com.adobe.granite.workflow.core.eventsupport.JcrToWorkflowEventService Unable to retrieve workflow instance: /etc/workflow/instances/2014-02-20/model_2924610957186695 com.adobe.granite.workflow.WorkflowException: Unable to retrieve workflow instance: /etc/workflow/instances/2014-02-20/model_2924610957186695 at com.adobe.granite.workflow.core.jcr.WorkflowManager.getWorkflowInstance(WorkflowManager.java:112) at com.adobe.granite.workflow.core.WorkflowSessionImpl.getWorkflow(WorkflowSessionImpl.java:578) at com.adobe.granite.workflow.core.eventsupport.JcrToWorkflowEventService.onEvent(JcrToWorkflowEventService.java:175) at org.apache.jackrabbit.core.observation.EventConsumer.consumeEvents(EventConsumer.java:249) at org.apache.jackrabbit.core.observation.ObservationDispatcher.run(ObservationDispatcher.java:161) at java.lang.Thread.run(Thread.java:722) Caused by: com.adobe.granite.workflow.model.VersionException: Version 1.11 does not exist for /etc[workflow-path]/jcr:content/model at com.adobe.granite.workflow.core.jcr.WorkflowModelManager.getWorkflowModel(WorkflowModelManager.java:96) at com.adobe.granite.workflow.core.WorkflowSessionImpl.getModel(WorkflowSessionImpl.java:279) at com.adobe.granite.workflow.core.util.NodeReader.createWorkflow(NodeReader.java:211) at com.adobe.granite.workflow.core.jcr.WorkflowManager.getWorkflowInstance(WorkflowManager.java:110) ... 5 more

I attempted to package up the workflows and re-install them but the same exception is thrown and the workflow fails. I'm running AEM 5.6.1.

Has anyone seen and/or been able to resolve this issue?